/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.test.positioning;

import java.util.LinkedList;

import javax.microedition.khronos.opengles.GL10;

import android.opengl.Matrix;

/**
 * A utility that projects
 */
public class Projector {
	
	// Singleton Instance
	private static Projector singleton;
	
	// Position Changers
	private LinkedList<PositionChangerByPixels> positionChangers;
	
	// Projector Infomation
	private MatrixGrabber mGrabber;
	private boolean mMVPComputed;
	private float[] mMVP;
	private float[] mV;
	private int mX;
	private int mY;
	private int mViewWidth;
	private int mViewHeight;

	/**
	 * Returns the Only Instance of the Projector
	 * 
	 * @return Projector
	 */
	public static Projector getInstance() {
		if (singleton == null)
			singleton = new Projector();
		return singleton;
	}

	/**
	 * Initialize the Projector's Variables
	 */
	private Projector() {
		mMVP = new float[16];
		mV = new float[4];
		mGrabber = new MatrixGrabber();
		positionChangers = new LinkedList<PositionChangerByPixels>();
	}

	/**
	 * Adds a PositionChanger to the PositionChangers List
	 * 
	 * @param pc
	 *            Position Changer to be Added
	 * @return True - Added<br>
	 *         False - Not Added
	 */
	public boolean addPositionChanger(PositionChangerByPixels pc) {
		return positionChangers.add(pc);
	}

	/**
	 * Removes a PositionChanger in the Given Position
	 * 
	 * @param i
	 *            Position of the PositionChanger
	 * @return Removed Object
	 */
	public PositionChangerByPixels removePositionChanger(int i) {
		return positionChangers.remove(i);
	}

	/**
	 * Update the Coordinates of the Stored PositionChangers using this
	 * Projector
	 */
	public void updatePositionChangersCoordinates() {
		for (PositionChangerByPixels pc : positionChangers)
			pc.updateCoordinatesByPixels(this);
	}

	/**
	 * @param x
	 * @param y
	 * @param width
	 * @param height
	 */
	public void setCurrentView(int x, int y, int width, int height) {
		mX = x;
		mY = y;
		mViewWidth = width;
		mViewHeight = height;
	}

	/**
	 * @param obj
	 * @param objOffset
	 * @param win
	 * @param winOffset
	 */
	public void project(float[] obj, int objOffset, float[] win, int winOffset) {
		if (!mMVPComputed) {
			Matrix.multiplyMM(mMVP, 0, mGrabber.getmProjection(), 0,
					mGrabber.getmModelView(), 0);
			mMVPComputed = true;
		}

		Matrix.multiplyMV(mV, 0, mMVP, 0, obj, objOffset);

		float rw = 1.0f / mV[3];

		win[winOffset] = mX + mViewWidth * (mV[0] * rw + 1.0f) * 0.5f;
		win[winOffset + 1] = mViewHeight
				- (mY + mViewHeight * (mV[1] * rw + 1.0f) * 0.5f);
		win[winOffset + 2] = (mV[2] * rw + 1.0f) * 0.5f;
	}

	/**
	 * @param win
	 * @param winOffset
	 * @param obj
	 * @param objOffset
	 * @return
	 */
	public int unProject(float[] win, int winOffset, float[] obj, int objOffset) {
		/* Transformation matrices */
		float[] m = new float[16];
		float[] in = new float[4], out = new float[4];

		if (!mMVPComputed) {
			Matrix.multiplyMM(mMVP, 0, mGrabber.getmProjection(), 0,
					mGrabber.getmModelView(), 0);
			mMVPComputed = true;
		}

		if (!android.opengl.Matrix.invertM(m, 0, mMVP, 0))
			return GL10.GL_FALSE;
		
		//Transformation of normalized coordinates between -1 and 1
		
		// Conversion Android pixCoords to OpenGL
		win[1] = mViewHeight - win[1];
		
		in[0] = (win[0] - mX) / mViewWidth * 2.0f - 1.0f;
		in[1] = (win[1] - mY) / mViewHeight * 2.0f - 1.0f;
		in[2] = 2.0f * win[2] - 1.0f;
		in[3] = 1.0f;

//		 MultiplyMatrixByVector4by4OpenGL_FLOAT(out, m, in);
//	      if(out[3]==0.0)
//	         return 0;

		android.opengl.Matrix.multiplyMV(out, 0, m, 0, in, 0);
		if (out[3] == 0.0f)
			return GL10.GL_FALSE;
		
		
//		out[3]=1.0/out[3];
//	    objectCoordinate[0]=out[0]*out[3];
//	    objectCoordinate[1]=out[1]*out[3];
//	    objectCoordinate[2]=out[2]*out[3];
		
		out[3] = 1.0f / out[3];
		obj[objOffset] = out[0] * out[3];
		obj[objOffset + 1] = out[1] * out[3];
		obj[objOffset + 2] = out[2] * out[3];
		
		return GL10.GL_TRUE;
	}

	/**
	 * Get the current projection matrix. Has the side-effect of setting current
	 * matrix mode to GL_PROJECTION
	 * 
	 * @param gl
	 */
	public void getCurrentProjection(GL10 gl) {
		mGrabber.getCurrentProjection(gl);
		mMVPComputed = false;
	}

	/**
	 * Get the current model view matrix. Has the side-effect of setting current
	 * matrix mode to GL_MODELVIEW
	 * 
	 * @param gl
	 */
	public void getCurrentModelView(GL10 gl) {
		mGrabber.getCurrentModelView(gl);
		mMVPComputed = false;
	}
}
